This invention relates generally to a structure of a heat exchanger.
Conventional heat exchangers usually have a structure in which a freely-rotatable hollow drum is housed in an outer casing, a heating or heated medium is made to flow through the outer casing, and a heated or heating medium is also made to flow through the hollow drum, in order to effect heat exchange between the media.
In a conventional heat exchanger of this type, however, the heat exchange efficiency is low between the rotating hollow drum and the interior of the outer casing. Although fins or arms are provided on the hollow drum to increase its surface area, or a stirring mechanism is provided for stirring the interior of the outer casing, the heat exchange can not be done uniformly from inside the outer casing, and a marked drop in the heat exchange efficiency inevitably occurs because factors associated with the heat exchange efficiency other than the heat transfer area from the hollow drum are not taken into consideration.
Although the fins or arms are provided projecting from on the peripheral surface of the hollow drum in a conventional heat exchanger to improve the heat exchange efficiency between the interior of the outer casing and the hollow drum, an improvement in the heat exchange efficiency can not be accomplished simply by increasing the surface area by means of fins or arms, and by stirring, but heat-transfer areas of passage of the heating or heated medium must also be increased. Conventional heat exchangers do not pay sufficient attention to this point.